The Neuroanatomv-lmaging Core (Core C) is an integral part of the Program, providing resources and support for structural analysis as required in each of the proposed studies. Core personnel include a Director, a Co- Director, a Technical Director, and a technician. The Director, Dr. Milner, has an internationally recognized reputation in the areas of light (LM) and electron (EM) microscopy, and an extensive number of publications in these areas (see publications (P) for Project 3). The Co-Director, Dr. Pierce, is an experienced quantitative anatomist, having conducted studies involving correlated EM and LM stereological analysis and reconstruction (see Biosketch). The facilities and services provided by this core will support; (a) the selective labeling of neuronal subgroups through tract-tracer injection methodologies; (b) the fixation and processing of rodent tissue for LM, confocal and EM analysis, (c) single and dual preembedding and postembedding immunolabeling of antigens, and antibody characterization, (d) in situ hybridization, (e) reactive oxygen species (ROS) and nitric oxide (NO) imaging and (f) image acquisition for both analysis and presentation. Analytic approaches supported by the Neuroanatomv-lmaging Core will include: plotting neuronal distributions, the stereological determination of neuronal number, EM serial analysis and reconstruction of portions of labeled neurons and their processes, fluorescent densitometry, and the quantification of EM immunolabeling patterns (such as determining the extent to which processes are double-labeled, or immunogold particles are partitioned between different types of membranes, or membranes and cytoplasmic compartments).